At present, molecular and turbomolecular pumps should avoid pumping certain gases because they are liable to condense on the pump walls at low temperature, and because of the compression exerted by the pump. These liquid or solid condensates can give rise to damage, obstruction, or jamming of the pump. The reason for this condensation is that present pumps are cooled in order to evacuate the heat dissipated by the driving electric motor, together with the heat developed by compressing the gas. Consequently, the temperature of the inside walls of the pump is close to ambient, thereby greatly encouraging condensation.
An object of the present invention is to provide a vacuum pump provided with means for avoiding any danger of condensation.